The present invention relates to optical connectors and more particularly to an array ferrule and a method of making an array ferrule for use in such optical connectors.
Communication systems have grown in complexity furthering the need for greater broadband capabilities. Optical communication systems have been employed in these communication systems and especially in broadband systems for meeting the need to transport large quantities of data, voice and other types of communications over a relatively compact network. Miniaturization of components in optical communication networks also continues to be necessary. Accordingly, multi fiber optical connectors such as the MT-RJ connector have become increasingly popular because of their ability to easily connect a plurality of fibers utilizing a standard form factor within the telecommunications industry. MT-RJ connectors have the capability of terminating a pair or a single row array of fibers utilizing a ferrule within the same connector housing that was previously used for a fiber pair termination.
One such connector has been developed by the MT-RJ Alliance including the companies of Hewlett-Packard, Fujikura, AMP, Siecor, and Usconec. The MT-RJ connector family utilizes an MT ferrule designed to hold 2, 4, 8, 12 or 16 fibers in a linear array. The MT ferrule is a precision molded solid part having tapered fiber receiving passageways which are loaded with a ribbon fiber array from a rear end. In line with the fiber array are a pair of pin receiving holes which are used to align the ferrule end faces of two mated ferrules. The pin holes must be precisely located with respect to the array of fiber receiving channels in order to insure proper alignment and to minimize optical signal attenuation between mated fiber end faces.
U.S. Patent Application Publication U.S. 2003/0016918 provides a multi fiber optical ferrule having a group of fibers terminated from a ribbon and arranged in a linear array. The ribbon is secured into the ferrule with epoxy introduced through a transverse window formed in the ferrule. Once the epoxy is cured, the fibers are cleaved and polished at the front end or mating face to complete the ferrule and fiber array assembly. The ferrule and fiber array assembly may then be loaded into a variety of connector housings which are part of the MT-RJ or other connector systems. Although that publication provides for a multi fiber optical ferrule having a group of fibers arranged in a linear array, it is desirable to increase the number of fibers which may be terminated by such an array ferrule. There is a need, however, to increase the density of fibers in the array while maintaining the same MT-RJ form factor and housing. It should be understood that this problem is not limited to the MT-RJ form factor, but that the need for high density extends to many fiber optic connector families. What is needed is a ferrule and method which is capable of increasing the density of fiber terminations within an existing optical connector housing.
The invention provides an array ferrule for use in a fiber optic connector. The array ferrule has a main body having a fiber receiving cavity which extends therethrough from a mating face to a rear end. Pin slots are formed in opposing side walls of the main body and are precisely located with respect to the fiber receiving cavity. In communication with each pin slot is a retention member slot for receiving a pin retention member. A plurality of fibers is precisely positioned within the fiber receiving cavity and an encapsulant substantially surrounds the fibers to substantially fill the fiber receiving cavity.
A method of making the array ferrule begins with providing a ferrule blank having a pair of preformed slots extending inward from the opposing side walls. The blank is precisely aligned on a mandrel which is placed within the fiber receiving cavity. Pin slots are broached in each side surface in the area of the preformed slots to form the ferrule main body. The ferrule main body is then positioned within a ferrule receiving opening of a central fixture such that locating pins of the central fixture are positioned within the pin slots. The fiber receiving cavity is then populated with a plurality of optical fibers which are accurately located using a plurality of combs over the ends of the optical fibers which protrude from the mating face. Finally, the fiber receiving cavity is filled with an encapsulant which is cured.